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3-D Tissue Imaging Improved via Adaptive Optics

Photonics.comApr 2012
CHAMPAIGN, Ill., April 27, 2012 — Real-time, 3-D microscopic tissue imaging could bring the future of medical imaging into focus through a new technique that computationally corrects for aberrations in optical tomography.

Precision is vital in medical imaging, where imperfect images can affect a doctor's ability to accurately diagnose a disease. Optical aberrations, such as astigmatism or distortion, are a serious problem for high-resolution imaging because they make areas of the image that should be in focus blurry or streaked.

University of Illinois engineers developed a method to computationally correct aberrations in three-dimensional tissue microscopy. From left, postdoctoral researcher Steven Adie, professor P. Scott Carney, graduate students Adeel Ahmad and Benedikt Graf, and professor Stephen Boppart. (Photo by L. Brian Stauffer)
Hardware-based adaptive optics can be attached to imaging devices to eliminate aberrations before the image reaches the lens, but such equipment can be expensive and unwieldy and can reduce the amount of light that enters the lens. Also, adaptive optics can focus on only one plane at a time, making 3-D imaging arduous and time-consuming.

Aberrations in imaging can make points appear as slashes or blurs. (Graphic by Steven Adie)
Researchers at the University of Illinois developed a technique called computational adaptive optics that removes the need for such cumbersome equipment. Using software instead of hardware, aberrations can be corrected after images have been made, using a program that can run on an ordinary computer. This enable researchers to focus on maximizing the amount of light that their instruments can gather, rather than worrying about minimizing aberration.

“Computational techniques allow you to go beyond what the optical system can do alone, to ultimately get the best-quality images and three-dimensional datasets,” said Steven Adie, a postdoctoral researcher at Beckman Institute for Advanced Science and Technology at the University of Illinois. “This would be very useful for real-time imaging applications such as image-guided surgery.”

Postdoctoral researcher Steven Adie talks about developing their technique to better view 3-D microscopy. (Video by Anne Lukeman)
The researchers demonstrated the technique in gel-based phantoms laced with microparticles as well as in rat lung tissue. They scanned the sample with an interferometric microscope, and the computer read the information and automatically corrected the image for the entire volume of the sample.

“Being able to correct aberrations of the entire volume helps us to get a high-resolution image anywhere in that volume,” Adie said. “Now you can see tissue structures that previously were not very clear at all.”

The researchers now plan to refine the software's correction algorithms and find further applications for the technology.

“We are working to compute the best image possible,” said Stephen Boppart, professor of electrical and computer engineering, of bioengineering and of internal medicine at the University of Illinois.

The research was funded in part by the National Institutes of Health and the National Science Foundation.

Optical components or assemblies whose performance is monitored and controlled so as to compensate for aberrations, static or dynamic perturbations such as thermal, mechanical and acoustical disturbances, or to adapt to changing conditions, needs or missions. The most familiar example is the "rubber mirror,'' whose surface shape, and thus reflective qualities, can be controlled by electromechanical means. See also active optics; phase conjugation.